Home Site Map News Organization
Download KML
Day 3-7 Precipitation
Day 3-7 Temperature
Day 3-7 Soils
Day 8-14 Precipitation
Day 8-14 Temperature
Day 8-14 Soils

Download Shapefiles
Day 3-7 Precipitation
Day 3-7 Temperature
Day 3-7 Soils
Day 8-14 Precipitation
Day 8-14 Temperature
Day 8-14 Soils

Hazards Archives

About Us
   Our Mission
   Who We Are

Contact Us
   CPC Information
   CPC Web Team

HOME> Expert Assessments>Hazards Outlook

U.S. Hazards Outlook - Made December 07, 2016

 Days 3-7Days 8-14Prob. Days 8-14
SoilsNot Available

Categorical Outlooks
Experimental Probabilistic Outlooks (Information)

Valid Saturday December 10, 2016 to Wednesday December 21, 2016

US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EST December 07 2016

Synopsis: Arctic high pressure is forecast to expand south and east from the northern Rockies and northern Great Plains from Dec 10 to 14. A low pressure system is expected to precede the arctic front and track across the upper Midwest this weekend. Multiple waves of surface low pressure are expected to push inland into the western U.S. during the next week to ten days. A strong area of upper-level high pressure is expected to remain anchored over the Bering Sea with arctic high pressure extending from northeast Alaska into the east-central continental U.S. during Week-2.

Hazards Detailed Summary

For Saturday December 10 - Wednesday December 14: Surface high pressure centered over the southern Appalachians is forecast to result in much below-normal temperatures (departures of 12 degrees F or more) across the Southeast on Dec 10. Hard freezes are expected as far south as the Florida Panhandle on Saturday morning.

A surface low is forecast to develop across the north-central high Plains by Saturday, Dec 10 and then track rapidly east to the Great Lakes. Moderate to locally heavy snow (4 inches or more) is expected to accompany this surface low as it tracks from South Dakota east to the Great Lakes. The GFS ensemble mean indicates precipitation amounts of 0.25 to 0.50 inches (liquid equivalent) in the outlined area for heavy snow.

Arctic high pressure is likely to result in much below-normal temperatures across the northern Great Plains, northern Rockies, and northeast Washington state through at least Dec 14. Model guidance remains consistent that this arctic surface high expands southeast across the Great Plains and east-central U.S. next week. The much below-normal temperature hazard is posted for areas where the minimum temperatures are forecast to average more than 12 degrees F below normal. The largest negative anomalies of 20 to 30 degrees F are forecast across the northern high Plains where minimum temperatures could fall to around -20 degrees F from Dec 10 to 14. Dangerous wind chills of -20 to -40 degrees F are also likely to accompany this arctic outbreak across the north-central U.S.

Strong cold air advection, following the passage of an arctic front, is forecast to renew heavy lake-effect snow downwind of the Great Lakes, beginning on Dec 13. Total snowfall amounts are expected to exceed one foot in the most favored snow belts south and east of the Great Lakes from Dec 13 to 15.

Waves of low pressure are forecast to bring periods of heavy rain and high-elevation snow (total amounts of more than 5 inches, liquid equivalent) to parts of the Pacific Northwest and northern California from Dec 10 to 14. There remains an increased risk of freezing rain across the interior Pacific Northwest where precipitation coincides with the shallow arctic air. Elsewhere, periods of heavy snow (more than 6 inches per 24 hours) are forecast across the interior West as individual shortwave troughs with enhanced Pacific moisture push inland from Dec 10 to 14.

Arctic high pressure over western Canada and anomalous easterly flow is expected to result in much below-normal temperatures across the Alaska Panhandle from Dec 10 to 14. The 6Z GFS ensemble mean generally indicates that temperatures will average 16 degrees F or greater below normal across the Alaska Panhandle.

For Thursday December 15 - Wednesday December 21: Ensemble means agree that anomalous ridging aloft persists across the Bering Sea and western Alaska through Week-2. Much below-normal temperatures are likely to affect the northern half of the continental U.S. and the Alaska Panhandle. The slight, moderate, and high risk of much below-normal temperatures is based generally on areas where the GEFS reforecast tool indicates daily minimum temperatures with a 20, 40, or 60 percent chance, respectively, of falling below the 15th percentile comparted to climatology. The 6Z GFS ensemble mean indicates temperatures averaging as much as 25 degrees F below normal across the northern Great Plains and upper Mississippi Valley early in Week-2. The GFS model continues to offer a colder solution for the Pacific Northwest compared to the ECMWF model.

Based on good model agreement and consistency, the heavy precipitation (rain and high-elevation snow) for the southern Cascades and northern Sierra mountains along with heavy snow across the interior West is maintained through Dec 15. Also, cold air advection is expected to prolong the lake-effect snow event through Dec 15. Although the potential exists for winter weather hazards across the east-central U.S. during Week-2, the development and subsequent tracks of any low pressure systems remain uncertain.

According to the latest U.S. Drought Monitor (USDM) valid on November 29, the coverage of severe or greater drought for the CONUS decreased nearly a half percent to 16.6%. Improvements were noted for portions of the Lower Mississippi Valley and New York state. While the most recent USDM shows deterioration of drought conditions in the Southeast, rains following the latest release may yield improvement for the next publication.

Forecaster: Brad Pugh


Click here to see a display of the GFS Ensemble Forecasts

Please consult local NWS Forecast Offices for short range forecasts and region-specific information.